Method for joining a jacket part to a core part

ABSTRACT

A method for joining a highly electroconductive core element ( 2 ) to a jacket element ( 1 ) made of refined steel. In said method, the electroconductive core element ( 2 ), such as a copper bar, and the joining agent element ( 3 ) are inserted in the jacket element ( 1 ), and at least the juncture area of the elements to be joined is thermally treated, so that there is created a metallurgical joint between the electroconductive core element ( 2 ) and the refined-steel jacket element ( 1 ).

[0001] The present invention relates to a method according to the preamble of claim 1 for joining a tube element and a core element together.

[0002] The method of the invention can be applied particularly in the manufacturing of the suspension bars for electrodes, particularly for permanent cathodes, used in the electrolysis of metals. The structure of the suspension bar of permanent cathodes and the joining of the plate part of the permanent cathode to the suspension bar is made problematic by the fact that in order to conduct a high electric power to the plate part, the suspension bar must contain some highly electroconductive material, such as copper, because acid-resistant steel has poor electroconductivity, and consequently it cannot be the sole material of the suspension bar. In the patent publication WO 00/17419, there are introduced alternative methods for manufacturing the suspension bar of a permanent cathode. These methods are typically complicated and/or require special devices. In arrangements manufactured according to the methods of the prior art, the electroconductive properties of the joint have not always been maintained in a satisfactory way, especially in the corroding conditions that prevail in the electrolytic processes of metals.

[0003] The object of the present invention is to realize a novel method for joining the tube element and the core element together. Another object of the invention is to realize a method that is economical as regards to manufacturing technology and well suited to the targets of usage for manufacturing the suspension bar of an electrode, particularly a permanent cathode.

[0004] The arrangement according to the invention is characterized by what is set forth in the appended claims.

[0005] The arrangement according to the invention has several remarkable advantages. By means of the method of the invention, there is achieved a good, electroconductive joint between the jacket element with a lower electroconductivity and the core element with a high electroconductivity. The method is easily implemented without special devices. The method is suited to be applied in the manufacturing of products of very different sizes and, on the other hand, in the manufacturing of varying quantities of products.

[0006] The arrangement according to the invention is explained in more detail below, with reference to the appended drawings, where

[0007]FIG. 1 illustrates a step of a method according to the invention prior to the welding of the second end plate, and

[0008]FIG. 2 illustrates a bar according to the invention prior to the heat treatment step.

[0009] The invention relates to a method for joining a highly electroconductive core element 2 to a jacket element 1 made of refined steel. In said method, the electrolytic core element 2, such as a copper bar, and the joining agent element 3 are inserted in the jacket element 1 with a poorer electroconductivity, and at least the juncture area of the elements to be joined together is thermally treated so that there is created a metallurgical joint between the electroconductive core element 2 and the refined-steel jacket element 1. The joining agent element 3 is essentially as long as the core element 2. Typically the joining agent element 3 consists mainly of tin. The quantity of the joining agent 3 depends on the size of the clearance between the jacket element 1 and the core element 2, as well as on how large a part of the surfaces between the core element and the jacket element should be joined together.

[0010] The jacket element is a tubular element with at least one end that is at least partly closed, at least during the thermal treatment. Typically the first end opening of the jacket element is closed, for instance by welding an end plate 5 thereon after the core element 2 and the joining agent element 3 are inserted in the tube. In the embodiment according to the drawings, also the other end opening of the jacket element is partly closed, for instance by welding an end plate 5 thereon after the core element and the jacket element are inserted in the tube. In that case an opening 7 is left at the end of the jacket element, at least for the duration of the thermal treatment. This can be achieved for instance by leaving the top edge of the welded seam 6 in the second end plate 5 unwelded. Typically the elements to be joined together are kept at an essentially horizontal position during the thermal treatment. Thus the tin, while melting, can penetrate to the whole junction area. During the thermal treatment, the molten tin dissolves copper from the copper bar serving as the core element 2 and creates tin bronze, which simultaneously begins to dissolve the inner surface of the refined steel tube serving as the jacket element 1, thus creating a metallic tin bronze joint between the core element 2 and the jacket element 1. In a typical case, the thermal treatment was carried out in a furnace, the temperature whereof was raised essentially over about 900° C.

[0011] According to another preferred embodiment, the thermal treatment of the elements to be joined together is carried out in a position that is essentially other than horizontal. In that case that end of the jacket element that is in a lower position is typically closed, at least up to the height of the desired junction surfaces.

[0012] The method according to the invention is suited to manufacturing the suspension bar of an electrode, particularly a permanent cathode. In this specification, the term ‘refined steel’ refers to stainless or acid-resistant steel. The term ‘copper’ refers to a material containing mainly copper, i.e. at least 50% copper. 

What is claimed is:
 1. An optical encoder comprising: a light source means; a scale having a reflecting means that is arranged so as to oppose the light source means; and a light-receiving means that receives a reflected light beam from the scale, wherein the reflecting means of the scale has an optical characteristic where a divergent light beam from the light source means is divided into a plurality of wave surfaces after repeating reflection at least twice, and respective light beams obtained as a result of the division are made to overlap each other at an arbitrary position.
 2. An optical encoder according to claim 1, wherein the light source means is a current constricting type LED having a plurality of light- emitting regions, the light-receiving means includes a photoelectric conversion element having a plurality of light-receiving windows, and the light-receiving means is produced by integrally packing the photoelectric conversion element, a signal amplifying means, an electrical division and interpolation means, and a light intensity compensating circuit for the light source means.
 3. An optical encoder according to claim 1, wherein when an air conversion optical path length from a light-emitting surface of the light source means to a substantial reflecting surface of the scale is referred to as gL, an air conversion optical path length from a light-receiving surface position of the light-receiving means to the reflecting surface of the scale is referred to as gP, a space between light-emitting points and a basic pitch of a light-receiving element group are referred to as P2, a pitch of the scale is referred to as Pi, one of a center wavelength of an output peak value of a light beam emitted from the light source means and a wavelength of a center value obtained through integration of spectral distribution is referred to as 2˜, and a natural number is referred to as n, gaps are set at gL and gP which are determined so that the following relations are satisfied within a range of n<1: P 2=2P 1, gP=gL=2n(2P ₁)²/λ, wherein a peak position of received light intensity is set so as to coincide with the range.
 4. An optical encoder according to claim 1, wherein when an air conversion optical path length from a light-emitting surface of the light source means to a substantial reflecting surface of the scale is referred to as gL, an air conversion optical path length from a light-receiving surface position of the light-receiving means to the reflecting surface of the scale is referred to as gP, a space between light-emitting points is referred to as P2, a basic pitch of a light-receiving element group is referred to as P2, a pitch of the scale is referred to as P1, and one of a center wavelength of an output peak value of a light beam emitted from the light source means and a wavelength of a center value obtained through integration of spectral distribution is referred to as λ, gaps are set at gL and gP which are determined so that the following relations are satisfied within a range of 1.5<n<2.5: P 2=2P 1, gP=gL=2n(2P ₁)²/λ, wherein a peak position of received light intensity is set so as to coincide with the range.
 5. An optical encoder according to claim 1, wherein the reflecting means is a micro roof mirror array produced by disposing, in one direction, a plurality of roof mirrors having two reflecting surfaces that are opposedly arranged at a predetermined angle, with each reflecting surface being a curved surface.
 6. An optical encoder according to claim 1, wherein a reflecting region of the reflecting means utilizes one of an internal total reflection action and a surface reflection action achieved by a translucent member.
 7. An optical encoder according to claim 6, wherein the reflecting region of the reflecting means utilizes metal specular reflection.
 8. An optical encoder according to claim 6, wherein the reflecting region of the reflecting means utilizes the internal total reflection action achieved by the translucent member, and a cylindrical lens is provided on an incident surface side of the reflecting means.
 9. An optical device comprising the encoder according to claim
 1. 10. A reflecting body comprising: a reflecting means produced by disposing, in one direction, one of a plurality of roof mirrors and a plurality of roof prisms each having two reflecting surfaces that are opposedly arranged at a predetermined angle, wherein the reflecting means has an optical characteristic where an incident light beam is divided into a plurality of light beams by the plurality of roof mirrors/roof prisms, a light beam reflected in succession by the two reflecting surfaces of each roof mirror is made to overlap reflected light from other roof mirrors/roof prisms at an arbitrary position.
 11. A reflecting body according to claim 10, wherein the same angle is formed by the two reflecting surfaces of each of the plurality of roof mirrors/roof prisms constituting the reflecting means.
 12. A reflecting body according to claim 10, wherein angles formed by the two reflecting surfaces of the plurality of roof mirrors/roof prisms constituting the reflecting means are changed in a continuous manner.
 13. A reflecting body according to claim 11 or 12, wherein the reflecting means is formed on one of a cylindrical surface and a spherical surface.
 14. A reflecting body according to one of claims 10, 11, and 12, wherein a light incident surface of the reflecting body is provided with a cylindrical lens.
 15. A reflecting body according to one of claims 10, 11, and 12, wherein the reflecting means forms a Fresnel zone plate.
 16. A reflecting body according to one of claims 10, 11, and 12, wherein the reflecting means converges incident light in a one-dimensional direction.
 17. A reflecting body according to claim 10, wherein an angle formed by the two reflecting surfaces is in a range of from 80° to 100°.
 18. An encoder comprising the reflecting body according to claim 10, wherein the reflecting body is applied to a reflection marker portion for outputting an origin of an encoder.
 19. An encoder comprising the reflecting body according to claim 10, wherein the reflecting body is applied to a reflection marker portion for detecting a commutation signal of an encoder for motor controlling.
 20. A printer apparatus comprising: one of the encoder according to claim 1 and the reflecting body according to claim
 10. 21. A video camera comprising: one of the encoder according to claim 1 and the reflecting body according to claim
 10. 